The present invention relates to the field of high density interconnect (HDI) modules.
In order to build a three-dimensional (3-D) module, a substrate stack of two or more individual HDI substrates need to be interconnected by means of metallic interconnects that can extend over the substrate edges. In most designs, at least two edge portions of the substrates have to be interconnected. Since each 3-D stack edge requires the same HDI processing which includes lamination, via drilling, metallization and passivation, the initial lamination holder should expose and preferably laminate two edge portions of the stack to the conductive carrier interconnects simultaneously. If this is done, subsequent HDI processing using processing fluids can be performed in parallel rather than in series, saving processing time and reducing cost. For further background on the fabrication of 3-D modules from stacked substrates, reference can be made to U.S. Pat. No. 5,699,234 issued to Saia et al. FIG. 7 in particular discloses a laminating side layer 38 bonded to edge portions of the stack and bearing interconnects formed by wet processing after the laminating layer is bonded to the stack. This side layer thus constitutes an interconnect carrier film. See also U.S. Pat. No. 5,107,586 to Eichelberger et al.
It is desirable to provide a stack lamination holder for suspending the stack firmly in place during lamination and to expose two stack edges simultaneously to the heat and pressure of lamination. After the resulting lamination of the interconnect carrier film to the stack edge portions, the holder must prevent subsequently applied processing liquids from reaching interior portions of the stacked substrates within the holder during the wet chemical processing steps. It is also desirable to provide a process which can perform carrier film lamination upon wrap-around stack edge contacts without the production of voids.